Generally, a known image forming apparatus includes a pair of side frames facing each other and an image forming portion configured to form an image on a recording medium and supported by the pair of side frames. The image forming apparatus may further include a lower frame that connects the pair of side frames below the image forming portion. The lower frame may be provided with some circuit boards such as a drive-control circuit board.
In a case where the lower frame is provided with a low voltage power supply board including a low voltage circuit configured to lower a voltage supplied from an external power supply to a specified voltage and supply the voltage to other apparatus, the low voltage circuit board needs to be covered with a shield member made of metal or a flame retardant resin. In other words, such a low voltage power supply board needs to be covered with a shield member made of sheet metal or a flame-retardant resin to constitute a fireproof enclosure so as to prevent spread of fire in case of the ignition of electronic components such as a capacitor. It is proposed that a drive control circuit board including such a low voltage power supply board is fixed on a sheet metal shield, which is fixed to the lower frame from below with a surface of the sheet metal shield on which the drive control circuit board is fixed facing up.